Composition for electrolytes for electrical etching.



TE SA S NT OFFICE.

JOSEPH H. WEEKS, OF RU'ILEDGE, PENNSYLVANIA, ASSIGNOR TO JACKSON S. WEEKS,

OF DELAWARE COUNTY, PENNSYLVANIA, AND RAYMOND M. WEEKS, OF PHILADEL- PHIA, PENNSYLVANIA, TRUSTEES.

COMPOSITION FOR ELECTROLYTES FOB, ELECTRICAL ETCHING.

No Drawing.

To all whom it may concern:

Be it known that I, Josnrn: H. WEEKS, a citizen of the United States, residing at Rutledge, in the county of Delawareand State of Pennsylvania, have invented certain new and useful Improvements in Composition for Electrolytes for Electrical Etching, of which the following is a specification. Y

My invention has for its ob ect the production of an improved electrolyte for use in electrical etching of metals.

The general subject matter to which this invention relates is discussed in my prior applications, Serial Numbers 88,362, 108,232, and 119,548, filed respectively April 1, 1916, July 8, 1916, and September 11, 1916. In the first of said applications, I have disclosed a method, apparatus, and certain compositions for electrolytes intended to be used therein; in the second application, I have described and claimed a process and composition, and in the third application, I have described and claimed certain improved apparatus. The electrolyte which I shall hereinafter set forth is adapted for use in the aforesaid processes, and with the aforesaid apparatus, although it is not necessarily limited thereto, and may be employed in other connections, and for other metals or alloys of metals than those therein specifically described. v

In the prior applications referred to, I have set forth a' method of etching plates in which a resistant image is produced on a plate, either by means of ink or powder, which is well known in the art, or by means of a special gelatin albumen enamel of my own invention. The plate so prepared is suspended in a suitable bath or solution and connected so as to form the anode terminal of a circuit supplied with current of suitable Voltage to produce the desired amperage or volume of current flow per unit area of the anode. The cathode terminal, which is also immersed in the bath or solu tion, may be of various types and of various materials. In my application I have de scribed carbon cathodes, and have set forth means for keeping the surface of the plate clean so that it shall be completely and uniformly exposed to the electrolytic action of the current, and for keeping the cathodes clean. and for preventing undercutting of the edges of the image or lines on the plate.

Specification of Letters Patent.

Patented Sept. 2,1919.

Application filed April 30, 1917. Serial No. 165,473.

The problems to be met are different from those presented in the electro-plating art,

because, in the latter, it is the deposition of metal which concerns the operator, and which must be even and regular, as Well as reasonably rapid; whereas, in the present cases, it is the removal of the metal by the current into or through the solution, which tended over a considerable period, and in the course of which the present invention and the others hereinbefore referred to have been produced, I have found that the composition of the electrolyte plays a very considerable part, not only in the regulation of the action on the plate, but in the uniformity of such action, and in maintaining said uniformity for any apprc :iable period of time.

Without going into detail at this time, into the chemical reactions or the steps in transference of the metals, which take Place with any particular composition, I may say generally that I have found it necessary to provide a solution which shall have, first, the proper conductivity; second, a capacity for absorbing and transferring the electrically displaced metal from, the plate without soon becoming saturated or clogged; third, no tendency to foul or coat or form bubbles or spots upon the plate, which would impede the free passage of the current and thereby mar the engraving; fourth, no tendency, or a reduced tendency, to foul and form sludge upon the cathode surface in such manner that it cannot be readily removed; and fifth, such elements and such a balance of forces and properties that its efficiency will remain unimpaired for a considerable period of time, and use.

The solution which I shall hereinafter set forth, and which has for its principal active element a borate or borates, either alone or in combination with certain other substances, mcets those conditions, and has enabled me, by actual test, to produce as good results with the last plate of a long series, as with the first one, for example the same depth of etching in the same length of time.

The present invention is correlated to and in most cases interchangeable with the inin combination with certain other substances.

The class of metals with which this electrolyte is useful is very large, including all.

the metals specified in my prior applications above referred to, and many others. The

metals most commonly employed in the engraving art are copper, brass, steel, and.

zinc, and the plates are employed for print ing, stamping, and for other purposes. In addition to the engraving of steel printing plates both in relief and intaglio, the manufacture of steel dies and plates for stamping metals is, in itself, very important, and by my process, and with my solutions, 1 can produce such dies and plates in much less time, and with much less expense, than where they are cut by hand accordin to the practice prior to this invention. W ere the plates are to be employed for printing, myinvention is specially important at the present time, because of the scarcity of high grade paper, and the necessity for having perfect printing plates in order. to produce satisfactory results on the cheap grade of paper now commonly employed, because of such scarcity.

Electrolytes are prepared, for the greatest efliciency and economy, for the particular metals to be etched. Wherever practicable, acombination is used in which the plate to be etched is kept clean Without wiping. This is especially requisite in very delicate work, as frequent wiping would tend to in An acid condition is desirable in all electrolytes to give stability to the same and to increase the conductivity. If the constituent salts do not render the electrolyte acid or sufiiciently acid for these purposes, an acid should be added. Some excellent electrolytes would promptly separate under,

electrolysis and promptly become useless were it not for the addition of the acid. Even if this doe-s not occur the life .of the electrolyte is shorter without acid and its conductivity less. Further in many cases the presence of an acid prevents precipitations in the electrolyte or on the cathode or on the anode or performs two or all of these functions.

lln some combinations where the ordinary acldsdo not keep the cathode or the anode clean or prevent precipitations in the bath,

this may in some instances be partly or wholly accomplished by the addition of a chromium salt, or by What is generally termed chromic acid (usually potassium dichromate'solution acted upon by sulfuric acid), although the action herein stated does not depend on the sulfuric acid in the chromic acid as that might independently be present in or added to the electrolyte under the head of acids. The chromium salts are also employed on account of their tendency to produce a smooth surface in'the anode where it is found that ordinarily the surface is'rough, smoothness of the anode jure the material of the image. In coarse ing'in power used thereby. For the reasons stated, some of my formulae do not give both a clean cathode and a clean anode.

The various use of borates with other salts and with or without acids, is in some instances to secure anode or cathode plate cleanliness or both, and to obtain electrolyte which shall form the loest. chemical combinations in themselves and with the anode,

shall have the longest life, and produce the smoothest etching, z'. e., to avoid rough grainy etching on either the sides of the lines or the bottom, and further, to secure a desirable speed which will admit of commercial etching of the various metals with being usually a desirable feature.-

Specifically stated, the solution to be claimed herein consists essentially of one or more of the borates of ammonium, barium, magnesium, manganese, potassium, sodium, and zinc.

While the essence of the invention is the use of a suitable borate, I may and do employ more than one, in combination, when required, but it is obvious that only those which will properly mix or combine can be simultaneously employed.

With the borates I may combine other salts with or without an acid. I may also employ as an additional element, a small quantity of a perchlorid, such as the perchlorid of ,iron, containing an excess of acid. This may be used in'lieu of one or more of the foregoing borates, and in such 7 case, no other acid is usually necessary. The principal function of-the separate acid, if added, 1s to increase the conductivity and prevent decrease in current density and tends in most cases to keep the face of the plate clean and to prevent disintegration of the solution.

As an example of a solution in which a borate and an acid are employed, I may give the following:

4 oz. fluid.

As an example of solutions in which a borate and one or more other salts are employed, I may give the following:

Saturated solution borax in water 2 oz. fluid. Aqueous solution ammonium chlorid to test Baum 2 oz. fluid. Muriatic acid C.. P oz. Ammonium borate saturated solution in Water containing slight excess of undissolved borate 3 oz. fluid. Sulfuric acid C. P. to clear above and slight excess Zinc nitrate 120 grains.

' Water 1 oz.

Sodium tartrate' 30. grams. Water 1 oz.

Ammonium sulfate 120 grains. 'Water 1 oz. Iron (per) chlorid solution testing 42 Baum 1,} oz. flu1d. Potassium oxalate 20 grains. Water 1 oz.

Potassium 'borate 120 grains. Water 3 oz. Ammonium nitrate 120 grains. 0 Water-- 3 oz. Muriatic acid 9; oz.

Magnesium borate saturated aqueous solution; 2 oz. fluid.

Iron oxalate saturated aque- .45 -ou solution 2 oz. fluid. Muriatie acid C. P 9 oz. fluid.

Potassium borate 120 grains.

Iron sulfate 120 grains. Willi 8 OZ. Muriatic acid C. P 5, oz,

Potassium borate 240 grains. Ammonium acetate 80 grains. Water 4 oz. Iron oxalate saturated aqueous solution L.. 2 oz. Muriatic acid C. P oz.

' It is to be understood that in the term borates I include those salts known as metaborates and pyro-borates. Among such'I have found one-of the most active in elecdium, or zinc,

trolytic etching to be sodium meta-borate, known generally as borax or borate of sodium.

It is also to be noted that in the claims, where I mention a borate, a chlorid, a sulfate, a tartrate, a nitrate or an oxalate, or a combination of any of these without mentioning a particularm'etal, I include in that term one or more of the salts from the same acid, that is ul'lG or more acetates, one or more borates, etc.

Having thus described my invention what I claim and desire to secure by Letters Patent 1s 1. In electrolytic etching, an anode carrying a resistant image to be etched, in combination with an electrolyte comprisin one or more of" the borates of ammoniumfbarium, magnesium, manganese, potassium, sodium or zinc.

2. In electrolytic etching, an anode carrying a resistant image to be etched, in combination with an electrolyte comprising one or more of the borates of ammonium, barium, magnesium, manganese, potassium, so-

. dium or zinc, with an acid.

3. In electrolytic etching, an anode carrying a resistant image to be etched, in combination with an electrolyte comprising one or more of the borates of ammonium, barium, magnesium, manganese, potassium, sodium or zinc, with a chlorid and an acid.

4. In electrolytic etching, an anode carrying a resistant image to be etched, in combination with an electrolyte, comprising one or more of the borates of ammonium, ba-

rium, magnesium, manganese, potassium, so I dium or zinc, with a chlorid, a sulfate and an acid.

5. In electrolytic etching, an'anode carrying a resistant image to be etched, in combination with an electrolyte comprising one or more of the borates of ammonium, barium, magnesium, manganese, potassium, sodiumorlzinc, with a chlorid, a sulfate, a tartrate and an acid. 1

6. In electrolytic etching, an anode carrying a resistant image to be etched, in combination with an electrolyte comprising one or more of the borates of ammonium, barium, magnesium, manganese, potassium, sowith a chlorid, a sulfate, a tartrate, a nitrate and an acid.

' 7. In electrolytic etching, an anode carrying a resistant image to be etched, in combination with an electrolyte comprising one or more. of the borates of ammonium, barium, magnesium, manganese, potassium, sodium or zinc, with-a chlorid, a sulfate, a tartrate, a nitrate, an oxalate and an acid. In testimony whereof I afiix my signature.

JOSEPH H. WEEKS. 

